Artificial horizon.



PATENIED DEC. 4, 1906.

J. MARSHALL.

ARTIFICIAL HORIZON.

APPLICATION FILED APB,5,1905.

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JOSEPH MARSHALL, OF SALMON, IDAHO.

ARTIFICIAL HORIZON.

Specification of Letters Patent.

Patented Dec. 4, 190,6.

Application filed April 5, 1905. Serial No. 253,996.

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Be it known that I, JOSEPH MARSHALL, a subject of the King of England, residing at Salmon, in the county of Lemhi and State of Idaho, have invented a new and useful Artiiicial Horizon, of which the following is a specification.

This invention relates to artificial horizons, and particularly to devices of that class employed in connection with octants, sextants, and quadrants for the purpose of taking an observation when the natural horizon is obscured.

A further object of the invention is to provide a device of this class in which the sights are so mounted and arranged that they will not be shifted by rolling or pitching of the vessel in heavy weather, and, further, to provide a device which when once placed on a level surface may be shifted back and forth without altering the position of the sights.

I/Vith these and other objects in view, as will more fully hereinafter appear, the invention consists in certain novel features of construction and arrangement of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the form, proportions, size, and minor details of the structure may be made without departing from the spirit or sacriiicing any of the advantages of the invention.

In the accompanying drawings, Figure 1 is a perspective view of an artificial horizon constructed in accordance with the invention. Fig. 2 is a vertical section of the same, one of the lens-tubes being shown in elevation. Fig. 3 is a transverse sectional view of a? portion of the instrument on the line 3 3 of Similar numerals of reference are employed to indicate corresponding parts throughout the several figures of the drawings.

The instrument is provided with a casing 10, having a flat bottom 11, which may be placed on a horizontal surface-such, for instance, as the top of the compass-and this casing forms a chamber for the reception of a body of liquid, preferably in the form of alcohol containing a percentage of water. The top ofthe casing is rounded and is provided with projecting tubular portions 14 and 15, at the ends of which are lenses 16 and 17, respectively, said lenses forming the ends of the chamber and serving to coniine the liquid therein, and at the top of the chamber is a filling-tube 1S, through which the liquid may be poured, the tube being closed by a screw-plug 19. The tube extends above the level of the top of the chamber, so that the latter may be completely filled, leaving no air-bubbles within the chamber. To the tubular end 15 is secured a tube 20, within the outer portion of which is a telescopicallyslidable tube 21, that may be provided with a lensor sight opening, as indicated at 22.

The bottom 11 of the casing is provided with one or more upstanding lugs 24, bearing a knife-edge 25, on which rests a depending lug 25', carried by the lower portion of a closed tank 26, the latter floating in the liquid and its upper end extending into the enlarged upper portion of the liquid-containing chamber. The top of the tank is provided with a pair of projecting arms 27, the outer ends of which are bent upward and carry sights 28, which when the instrument is perfectly level are arranged in horizontal alinement with each other and in theV horizontal axial line of the telescopic tubes.

Arranged within the upper portion of the tank 26 is a knife-edge fulcrum-bar 30, carrying a weight 31, the fulcruin-bar being in vertical alinement with the fulcrum 24 when the sights 2S are in horizontal alinement. The opposite sides of the upper portion of the chamber are provided with transparent panels 34 in alinement with the outer portions of the arms 27, so that the movement of the latter may be visible.

When the bottom 11 is resting on a perfectly-level surface, the two fulcrums 24 and 3() will be in vertical alinement with each other, and the two sights 28 will be in horizontal alinement with each other and in the horizontal axial plane of the telescopic tubes. Should there be any variation of the supporting-surface from a horizontal plane, the weight 31 will instantly swing so that its center of gravity will be to one side of the vertical plane, including the two fulcrums 24 and 30, and this will tend to swing the tank in the corresponding direction; but the movement of said tank will be retarded by the body of liquid in which it is immersed, so that while the weight is instantly responsive to variations the liquid will prevent any rapid oscillatory movement of the tank, and the sights will move very slowly to and from position until the level is resorted. When placed. on a level surface, the instrument may IOO IIC

be moved to and fro without danger of oscillating the sights, owing to the retarding effect of the liquid, and this will permit taking a correct observation without waste of time.

The instrument may be connected in the usual manner to any ordinary type of altitude instruments.

Having thus described the invention, what is claimed is# 1. In an artificial horizon, a liquid-containing vessel, a buoyant tank immersed therein, sights carried by the tank, and a pivotally-mounted weight disposed within the tank and freely responsive to variations in the level of the instrument.

'2. In an artificial horizon, a casing filled with liquid, a buoyant tank immersed in the liquid, sights carried by the tank, and a pi votally-mounted weight having its fulcrum at the vertical center of the tank.

3. In an artificial horizon, a casing filled with liquid, and having a telescopic tube connected to the upper portion thereof, a buoyant tank having its lower portion pivoted within the casing, sights carried by the upper portion of the tank, and a freely-movable weight suspended within the tank, the fulcrum of the weight being in vertical alinement with the fulcrum of the tank.

4. In an artificial horizon, a liquid-containing casing, a telescopic tube connected to the upper portion thereof, transparent panels vin the upper portion of the casing, a tank pivot-ed to the lower portion of the cas ing and immersed in the liquid therein, arms projecting from the opposite sides of the upper portion of the tank, sights carried by the arms, and a weight suspended from the tank, the fulcrums of the yweight and tank being in vertical alinement when the sights are in horizontal alinement.

In testimony that I claim the foregoing as my own I have hereto afxed my signature in the presen ce of two witnesses.

JOSEPH MARSHALL.

Witnesses:

TIMOTHY DORE, F. W. PHIsTE. 

